大面积压实填土荷载作用下群桩负摩阻力计算的新方法  

A new method to calculate negative friction of pile group under large-area compacted fill load

作　　者：薛祥[1] 邱冬瑞[2] 郑毅 朱春杰 侯东利[1] Xue Xiang;Qiu Dongrui;Zheng Yi;Zhu Chunjie;Hou Dongli(BGI Engineering Consultants Ltd.,Beijing 100038,China;Beijing Building Construction Research Institute Ltd.,Beijing 100039,China)

机构地区：[1]北京市勘察设计研究院有限公司,北京100038 [2]北京市建筑工程研究院有限公司,北京100039

出　　处：《工程勘察》2020年第3期9-16,共8页Geotechnical Investigation & Surveying

摘　　要：有关负摩阻力的现场试验和理论分析针对单桩的较多,而针对群桩的相对较少,现行规范的做法即为引入一个群桩负摩阻力群桩效应系数,而该系数不能较好地反映布桩形式、基桩尺寸及其对负摩阻力传导过程中的遮挡、约束等效应。本文基于相似原理推导了三桩、四桩及六桩群桩负摩阻力计算公式,分析并提出了五桩梅花形布桩的群桩负摩阻力计算公式,并对相关参数进行了影响分析。相关公式形式与现行规范一致,但本文群桩负摩阻力效应系数的物理意义更明确,同时重点考虑了影响负摩阻力发挥的主要因素,即布桩形式、桩径、桩距和桩数。将负摩阻力传导过程中因桩体对传力路径的遮挡、桩体对桩心土的约束、桩心土层的竖向变形及基桩尺寸效应等因素进行了综合考虑,并通过公认的研究成果确定的边界条件,求解了该综合影响系数。研究分析及工程实例应用表明,该方法推导的相关公式符合实际、合理可靠、计算方便,可供同行参考使用。There are many field tests and the theoretical analysis of negative friction resistance for single pile,and relative less for group pile.A negative friction coefficient of pile group effect is introduced in the current code.However,this coefficient cannot provide a good response to pile arrangement,pile size and its shielding and constraint effects in the process of negative friction transmission.Based on the similarity principle,the formulas to calculate the negative friction of three-pile,four-pile and six-pile group are derived in this paper,and the calculation formula of negative friction of five-pile with quincunx arrangement group is put forward,and the influence of related parameters is analyzed.The formula form is consistent with the current code,while the physical meaning of negative friction effect coefficient of pile group is clearer,and the main factors affecting the negative friction,such as pile arrangement form,pile diameter,pile distance and pile number etc.,are mainly considered.In the process of negative friction conduction,the factors such as the shielding of the force transfer path by the pile shaft,the constraint of the pile on the core soil,the vertical deformation of the core soil and the size effect of the pile are overall considered.The combined influence coefficient is solved according to the boundary conditions determined by the generally accepted research results.The analysis and the application show that the relevant formulas derived by this method are consistent with the actual situation,reasonable and reliable and convenient in calculation.It can be referred by the similar project.

关 键 词：大面积荷载 群桩 负摩阻力 群桩负摩阻力效应系数 相似理论 

分 类 号：TU433[建筑科学—岩土工程]